These embodiments relate to the field of dampers for springs, and more particularly to the damping of valve springs in engines. In order for four cycle internal combustion engines to run there needs to be a way of allowing the fuel-air mixture into the combustion chamber. When the fuel-air mixture has been burned, then the exhausted fuel-air mixture and combustion products must exit the combustion chamber. This has been done in the background art by providing at least one valve that opens and closes to allow the fuel-air mixture into the combustion chamber and traditionally at least one other valve to allow the spent fuel-air mixture and combustion products to leave the combustion chamber. The valves traditionally have springs which interact with the valve and are provided typically with a rotating cam to depress and release the valve.
The valves are opened by having the cam pressing on the valve forcing the valve towards the combustion chamber thus opening the valve and compressing the valve spring. When the valve is released the valve spring moves or returns the valve to the closed position. When the valve is opened the spring compresses and upon release of the valve, the spring returns the valve to the closed position.
This type of system works relatively well for most applications, but today with the smaller higher revolution per minute (rpm) engines, the need for decreased weight in vehicles, the need for higher efficiency engines and other reasons, the current valve spring system is not as desirable. As these smaller engines are operated at higher rpms for longer periods of time, the valves springs do not have time to completely stop oscillating when the valve is fully engaged and when the valve is fully released. This oscillation of the valve springs can lead to leakage when the valve is released and decreased flow when the valve is engaged to allow fuel and air into the cylinder. The valves can also float or flutter, meaning that the valves are not operating as efficiently as would be desired.
One way to discourage the float or flutter is to get the valve and specifically the valve spring to stop oscillating when opened and closed. Once the valve is closed, in a perfect system, both the valve and spring would stop moving. Conversely, once the valve is opened, both the valve and spring would stop moving. This does not occur in the real world and the valve spring continues to move up and down, or oscillate, for a finite time period and then stops. It is desirable to have the spring stop moving as quickly as possible when compressed and also when released.
Much of the background art also uses a separate valve stem seal to discourage the lubricating oil from penetrating into the combustion chamber. It would be beneficial to have this valve stem seal incorporated into a polymer damper to decrease manufacturing costs and also to ease assembly.
The damping of oscillations has traditionally been done by engineering the spring or spring materials to decrease this spring oscillation. Current engineering has reached the limit for damping these oscillations with spring engineering and spring materials. Some background art shows the use of dampers attached to the spring to lessen these oscillations. Much of the art that is known uses a steel damper. A steel damper only provides a point contact between the spring and the damper because of the relative inelasticity of the steel. The applicant uses a polymer for the damper which is then held against the surface of the spring by radial force provided by a band or ring acting as a spring element. A polymer damper can conform to the shape of the spring coils allowing more surface area contact against the damper and hence more efficient damping.
A damper can be any material that will stop a spring from oscillating. Various embodiments have been developed to stop the spring from oscillating such as a dual spring system, installing a damper on the outside of the spring, installing a damper on the inside of the spring. Many of the current systems have significant disadvantages to them that do not allow the optimum damping of the valve springs. These systems can be costly and difficult to install and maintain and some require re-engineering the cam shafts and cylinder heads where the valves and valve springs are located.
For the foregoing reasons, there is a need for a spring damper that will discourage the spring from oscillating when the spring is compressed and released.